NH‐Heterocyclic Aryliodonium Salts and their Selective Conversion into N1‐Aryl‐5‐iodoimidazoles

Abstract

Abstract:The synthesis of N-arylimidazoles substituted at the sterically encumbered 5 position is a challenge for modern synthetic approaches. Here we report a new family of imidazolyl aryliodonium salts that serve as stepping stones on route to the selective formation of N1-aryl-5-iodoimidazoles; the iodine can now act as a "universal" placeholder to be transformed into further substituents. These new λ 3 -iodanes are produced by treating the NH-imidazole with ArI(OAc)2, and are converted to N1-aryl-5-iodoimidazoles by a selective Cu-catalyzed aryl migration. The method tolerates a variety of Ar fragments and is also applicable to substituted imidazoles.

ChemInform Abstract: NH‐Heterocyclic Aryliodonium Salts and Their Selective Conversion into N1‐Aryl‐5‐iodoimidazoles.

“…Ap reliminary investigation also revealed that the coordination of N-Me-benzimidazole to the Cu I center may disfavor the binding of two molecule of 3 to the same copper center, hence enforcing an intramolecular phenyl transfer. [21] In agreement with Scheme 5, the preformed zwitterionic 3 was also an excellent substrate even in the absence of abase [Eq. (1)].…”

Competing Pathways in O‐Arylations with Diaryliodonium Salts: Mechanistic Insights

“…The competition between ligand coupling and aryne formation in arylations of hydroxide with diaryliodonium salts 1 a , 1 c , and 1 d was studied by DFT calculations using two different functionals (B3LYP‐D3, M06‐2X) commonly used for hypervalent iodine reactions . We started to investigate the reaction between 1 d and hydroxide in CH 2 Cl 2 (Figure ) .…”

“…The SDD basis set with an applied effective core potential (MWB46) was used for iodine, Pople's triple‐zeta basis set with added polarization and diffuse functions (6–311+G(d,p)) were used for N, O, F, Cl and Na atoms while the triple‐zeta basis set with added polarization (6–311G(d,p)) were used for the H , C and S atoms. Several iodine(III) reactions have recently been studied by DFT using similar setups . The systems were studied in both CH 2 Cl 2 and H 2 O using the polarizable continuum model (PCM, Surface=SES, Radii=UFF), and the results in H 2 O are given in the Supporting Information.…”

Atom-economical group-transfer reactions with hypervalent iodine compounds

“…A different approach towards the functionalisation of heterocycles was taken by Shafir, Lledós, and co-workers, who investigated the intrinsic conversion of novel N-heterocyclic aryliodonium salts 1b [ 35 ]. Under the influence of base, copper catalyst and N -Me-benzimidazole as a ligand, the heterocyclic aryliodonium salt 1b was converted into the N 1-aryl-5-iodoimidazole 18 as the major isomer ( Scheme 10 ).…”